Subterranean termites in general and the Formosan subterranean termite (FST) in particular are very serious urban pests not only in the United States but also in many countries throughout the world. In the United States, in addition to the native subterranean termites, several southern states and Hawaii are infested with the exotic Formosan subterranean termite (FST), Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). In addition to infesting wooden structures the FST also infects live trees. Established colonies of foraging subterranean termites, for example Reticulitermes spp and Coptotermes formosanus, are difficult to control. These termites are known to cause colossal destruction of human property resulting in great economic loss. These termites are known to cause an estimated two billion dollars in preventive control, damage and repair costs each year.
The subterranean habitat of such termites makes it very difficult to treat infestation sites with conventional insecticides. It has become increasingly apparent that widespread use of synthetic chemical pesticides has caused detrimental environmental effects that are harmful to humans. Residual pesticides have been found in food, ground water and throughout the environment. Many of these pesticides are toxic or carcinogenic or are otherwise detrimental to humans and animals as well as fish. The inventory of conventional insecticides is greatly reduced because of stricter restrictions and regulatory guidelines based on environmental concerns and safety measures. Currently, baits containing chitin synthesis inhibitors (which disrupt molting), is the main tool used for termite control. In spite of being effective, it has two drawbacks; the termites have to first find the bait and additionally the process of colony elimination may take anywhere up to three months. The latter projection is based on the fact that only about 1% of the termite workers in a colony molts each day.
The previously referred to regulatory guidelines have encouraged a search for potentially less dangerous pesticides by restricting the use of certain synthetic pesticides or elimination of certain effective pesticides from the marketplace and reduced the ability to control pests. Therefore, natural products have become of possible interest because they are generally safer to humans and the environment than synthetic pesticides. Some natural products, particularly those that are volatile, have been studied for termite control (Wilkins, Mater. Org. 27: 47-65 (1992); Bläske and Hertel, J. Econ. Entomol. 94: 1200-1208 (2001); Tellez et al., Sociobiology 41: 153-167 (2003); Park and Shin. J. Agric. Food Chem. 53: 4388-4392 (2005); Raina et al., J. Econ. Entomol. 100: 880-885 (2007). Cornelius et al., J. Econ. Entomol. 90: 320-325 (1997) determined the toxicity of monoterpenoids and other natural products to C. formosanus in test tubes containing sand treated with these compounds. However, in most cases tests were carried out in Petri dishes, which do not take into account the cryptic nature of subterranean termites. Many a time very high doses have been used to demonstrate efficacy of a chemical. As example, Bessette U.S. Pat. No. 6,858, 653 claims that about 28 mg (example 1) of several plant essential oils, applied to glass Petri dishes, killed 100% of drywood termites in 1 hr. It is also to be noted that these tests involved potential physical contact with the test substances, and were performed in an environment that does not simulate the natural soil and wood environment of the FST. Whereas, some of the plant essential oil components, such as carveol, citronellal, p-cymene and geraniol, were claimed to cause high mortality of drywood and other termites in Petri dish assays, we found them to be totally ineffective against termites in soil and wood.
Current termite management practices include the use of baits placed around properties to be protected. A major drawback of the baits is that termites have to first find these baits and the treatments are costly and often time consuming
In the southern United States, fire ants Solenopsis invicta, are a significant pest. For example, foraging fire ants are known to destroy young citrus trees, growing crops, and germinating seeds. Fire ants are omnivorous, feeding on almost any plant or animal matter and they damage young plants by gnawing holes in roots, tubers, stalks, and buds. The fire ant population has increased so rapidly that they are responsible for the major destruction of crops such as soybeans, potatoes and other vegetables in the farming regions of the United States where they have taken over. They have had a major impact on ground nesting animals and they are a menace to both humans and domestic animals alike. Their venom can cause health problems for humans who are hypersensitive to their venom. For a great number of years there has been a need to control the spread of black and red imported fire ants that are invading ever-increasing areas of the United States. With each passing year they spread further north, east and west affecting more States and causing hundreds of million dollars worth of damage per year.
One approach to control fire ant has been to employ synthetic chemical pesticides, but these have met very limited success. Moreover, these synthetic chemical pesticides can also pose grave environmental hazards. Federal agencies of the US government have imposed restrictions on some chemicals in an effort to protect the environment from the harmful toxic effects produced by these chemicals. Among the chemicals banned or restricted in use by governments are: DDT, Chlorodane, Lindane, Aldrin, Heptechlor, Dieldrin, and Mirex. Mirex (perchloropentacyclodecane) was found to be one of the most effective fire ant killers, however since its use has been banned in the United States because it has been found to be a, bioaccumulative, and toxic pollutant, the fire ant population has increased rapidly.
There are still a number of commercial pesticide products on the market currently. These pesticides are typically contact poisons and are effective in killing a wide variety of insects. One which specifically targeted fire ants is the AMDRO® a hydramethylnon-based hydrazone insecticide product (trademark of Central Garden & Pet Company Corporation). This product is a delayed-action pesticide advertised to be effective against fire ants because it is eventually ingested by the queen. When the queen is killed, the colony vanishes and the mound is destroyed. However, AMDRO has a number of drawbacks. AMDRO loses much of it's effectiveness following contact with moisture. This is a serious shortcoming, since much of the domain of imported fire ants is along the southern coastal states of the United States where rainfall is plentiful. AMDRO also has a short shelf life after the container has been opened.
Fire ants have a significant economic impact on agriculture in infested areas. Additionally, telecommunication companies spend substantial amounts of money each year on treating their electrical equipment to prevent fire ant invasion because fire ants are attracted to electrical fields and can short out electrical equipment. Moreover, farm equipment can be damaged by large fire ant mounds. Fire ants also present a problem to wildlife, such as with ground nesting birds and animals. Furthermore, Fire ants are known to excavate the soil from under roadways causing damage.
Fire ants also pose a health care problem to the millions of people that are stung by them. Since a significant number of those people require medical care. Additionally it has been reported that fire ant stings are also blamed for human deaths each year. Thus, because of the problem fire ants present there is increasingly greater interest in controlling these fire ants.
This interest has resulted in much research and resources being expended through the years to develop compositions and methods for controlling fire ants. One type of desirable composition which would be of great interest would be a non-toxic naturally occurring reagent which could repel, or keep ants from invading a particular area or object.
Current methods for controlling structural infestations of carpenter ants include sanitation of potential and current nest sites, minimizing access to structures (e.g., preventing the contact of tree branches with a structure), and the application of insecticides to repel (perimeter spray barriers) and/or eliminate carpenter ants. The use of boric acid dust in dry, wall voids is reported to be effective for up to 20 years (Hansen and Akre, supra).
Recommendations for the chemical control of established structural infestations in the home are often accompanied with warnings of possible hazards to the applicator as well as children and pets. Alternative control methods such as effective biological control agents have not been found (Akre, R. D., L. D. Hansen, A. L. Antonelli [1989] Ext. Bull. Washington State Univ. Coop. Ext. Serv. 1989 rev. no. EB 0818, 6 pp.). A need clearly exists for a safe, effective biological control agent for carpenter ants.
One aspect of the present invention is to provide significantly effective compositions or formulations of naturally occurring compounds, particularly effective at significantly low concentrations, and chemicals therefor that are able to control and kill termites not only by vapors that can be carried by air to a target site to control or kill the termites but that can effectively penetrate wood and soil environments where the termites are found so as to control and kill them within that environment. Another aspect of this invention is to provide significantly effective compositions or formulations of naturally occurring compounds, particularly effective at significantly low concentrations, and chemicals therefor that are able to control and kill fire and carpenter ants not only by vapors that can be carried by air to a target site to control or kill the fire ants but that can effectively penetrate soil environments where the fire ants are found so as to control and kill them within that environment. A further aspect of the invention is to provide significantly effective compositions or formulations of naturally occurring compounds, particularly effective at significantly low concentrations, and chemicals therefor that are able to control and kill both termites and fire and carpenter ants. Yet another aspect of this invention is to provide such significantly effective compositions or formulations of naturally occurring food grade compounds, particularly effective at significantly low concentrations that are both effective against fire and carpenter ants and termites and at the same time is generally non-toxic to humans, biodegradable and considered to be environmentally safe.